Middle distillate fuels containing alkylene polyamine substituted sulfonates



United States Patent "ice MIDDLE DISTILLATE FUELS CONTAINING AL- 'KYLEls lE POLYAMINE SUBSTITUTED SULFO- NATE Earl R. Wieland, New Providence, NJ, assignor to Esso Research and Engineering Company, a corporation of Delaware No Drawing. Application September 17, .1957 Serial No. 684,408

The present invention relates to improved hydrocarbon oil compositions and more particularly relates to improved petroleum middle distillate fuels which have been stabilized against oxidative deterioration by the incorporation therein of from about 0.05 to 1% by weight of an alkylene polyamine sulfonate.

Petroleum middle distillate fuels such as heating oils, diesel fuels, jet engine fuels and similar fuel products boiling in the range between about 300 F. and about 900 F. generally contain small amounts of unsaturated hydrocarbons and other relatively unstable materials which may be readily oxidized. During the storage of such fuels, these unstable constituents react to form sludge Patented Feb. 2, 1960 bons with concentrated sulfuric acid or oleum. Acid and sediment which may lead to the plugging and fouling of filters, fuel lines and orifices in engines and fuel systems in which the fuels are used. These difliculties are particularly pronounced in the case of jet engine fuels because of the high temperatures to which such fuels are subjected prior to their introduction into the engine combustion chambers. Modern high speed jet aircraft engines, both military and civilian, are provided with heat exchangers in order to cool the lubricating oil and prevent its thermal degradation. Jet fuel is circulated through these heat exchangers as a cooling medium and as a consequence is often held at temperatures as high as 300 to 400 F. for prolonged periods before it is burned in the engine. Reductions in fuel flow and engine power, and in'extreme cases flame-outs, occur as a result of the fouling of jet engine fuel systems by sediment formed during the exposure of fuel to high temperatures.

Additive materials have been used in the past in order to improve the stability of petroleum middle distillate fuels and a number of such additive materials have been proposed for use in overcoming the problems described above. In testing additive agents suggested by the prior art for use in heating oils, such as metal naphthenates and sulfonates, however, it has been found that such materials in general are not sufficiently effective to permit their use in jet fuels and similar fuel products which are subjected to severe oxidizing conditions.

In accordance with the present invention, the instability of petroleum middle distillate fuels boiling between about 300 F. and about 900 F. is overcome by incorporating in such fuels small amounts of an alkylene polyamine sulfonate containing about 2 to 4 carbon atoms in the alkylene polyamine group. It has been found that these materials, when added in concentrations of from about 0.05% to about 1% by weight, greatly improve the stability of middle distillate fuels under conditions such as those encountered in jet engine applications and are considerably more effective than other stabilizing additives. Additive concentrations between about 0.05

' and about 0.1% by weight are preferred.

. seal oil.

' treating with sulfuric acid or oleum is widely used in the manufacture of lubricating oils, white oils and similar highly refined petroleum products and the acid oil obtained from such treating may be advantageously employed as the sulfonic acid in preparing the alkylene polyamine sulfonates. Synthetic sulfonic acids such as those obtained by similar acid treatment of alkyl aromatic hydrocarbons prepared by alkylating benzene, toluene, naphthalene and similar aromatics with a polyolefin such as polypropylene containing from about 9 to about 15 carbon atoms per molecule may also be used. Synthetic sulfonic acids prepared in this manner which have been found to be particularly effective are dinonyl naphthalene sulfonic acid and polypropyl benzene sulfonic acid. Other alkylene polyamines which may be reacted with the sulfonic acid to produce the sulfonates include diethylene diamine, diethylene triamine, and trimethylene diamine. Ethylene diamine is preferred, however, because of its low molecular weight and its primary amine radicals.

The alkylene polyamine and sulfonic acid may be reacted in approximately theoretical proportions as determined from the acid number of the acid oil or sulfonic acid. The reactants may be mixed and heated at a temperature of from about to F. for a period of from 1 to 3 hours while providing agitation in order to insure complete reaction. The reaction is an exothermic one and a small temperature rise normally takes place. At the end of the reaction period, the product may be filtered to remove any haze present. The reaction mixture thus obtained may be added directly to the oil or, if preferred, the alkylene polyamine sulfonate may be separated from the reaction mixture by procedures well known to those skilled in the art and then added to the oil.

Typical properties of ethylene diamine sulfonate prepared by the reaction of ethylene diamine with a synthetic sulfonic acid obtained by the acid treatment of dinonyl naphthalene as described above are as. follows:

50% solution in mineral seal oil Specific gravity 0.940-0.950 Viscosity, SUS at 210 F 295 The alkylene polyamine sulfonates may be employed as stabilizing additives for petroleum distillate fuels boiling in the range between about 300 F. and about 900 F. Typical of such fuels are heating oils falling within grades 1 and 2 as set forth in ASTM Specification D-39648T, diesel fuels falling Within grades 1D, 2D and'4D of ASTM Specification D-975-51T and jet engine fuels such as those covered by US. Military Specifications MIL-F-5624C, MIL-F-25524A and MIL-F- The eifectiveness of the alkylene polyamine sulfonates as stabilizing agents for middle distillate fuels can be readily seen by considering the results obtained in a series of experiments in which the stabilities of jet fuels to which small amounts of ethylene diamine sulfonate had been added were tested and compared with the stabilities of the same fuels Without the sulfonate. The ethylene diamine sulfonate used was prepared by the reaction of ethylene diamine with dinonyl naphthalene sulfonic acid and was added in a 50% solution in mineral The tests were carried out in apparatus closely resembling a scaled-down turbo jet fuel system. The fuels were pumped from a supply tank through a screen and rotarneter to an annular aluminum heat exchanger where they were heated to the test temperatures. They were then passed through a sintered metal filter held at a temperature 100 F. above the fuel temperature. Fuel erformance was measured by the time required for the pressure drop across the filter to increase by 25 inches of mercury or by the pressure increase which occurred in 300 minutes, Whichever took place first.

The base fuel used in the first test was a kerosine having the following inspections:

Gravity, API 41.9 Viscosity, centistokes at 100 F. 1.89 Freezing point, F. 30 ASTM distillation- Initial boiling point, F. 338 point, F. 376 50% point, F. 450 90% point, F. 510 Final boiling point, F. 540 Smoke point, mm. 22 Olefins, vol. percent 1.7 Aromatics, vol. percent 11.3 Sulfur, wt. percent 0.073 Flash point, F. 130 Heat content, B.t.u./# 18551 Further tests were carried out in the same manner using a jet engine fuel as defined by US. Military Specification MILF-5624C. The results obtained in these tests are shown in the following table. The additive concentrations are expressed in terms of the active ingredient, ethylene diamine dinonyl naphthalene sulfonate. The merit rating used as a means for measuring the fuel performance is a function of the pressure drop across the filter and the length of the run. A merit rating of 500 in this standardized test is equivalent to a pressure drop of 12 inches of mercury across the filter in 300 minutes and has been established by actual service tests as an acceptable stability level for turbo-jet fuels for aircraft.

Efiect of allcylene polyaimine sulfonates on aviation turbo-jet fuel stability From the above data it can be seen that the addition of the ethylene diamine sulfonate in a concentration of 0.05 wt. percent markedly improved the stability of the .about 900 F.

fuel and raised it to an acceptable level. In concentrations below about 0.05 Wt. percent, the ethylene diamine sulfouate is not a satisfactory stabilizing additive. Simiiar te ts carried out with commercial stabilizing additives at similar concentrations showed that those additives were unsatisfactory and that in some cases they actually had deleterious effects upon fuel stability.

Although the above described tests were carried out with kerosine and jet fuel, it will be understood that the applicability of alkylene polyamine sulfonates as stabilizing additives is not limited to those specific fuels and that they may advantageously be used in any petroleum middie distillate fuel boiling between about 300 F. and Similarly, it will be understood that the fuels of the present invention may contain other additive materials intended to combat other fuel deficiencies.

What is claimed is:

1. A petroleum distillate fuel boiling between about 300 F. and about 900 F. stabilized by the incorporation therein of from about 0.05% to about 0.1% by weight of an alkylene polyamine salt of a sulfonic acid selected from the group consisting of petroleum sulfonic acid and synthetic sulfonic acid prepared by the sulfonation of an alkylated aromatic hydrocarbon, the alkylene polyamine group of said salts containing from about 2 to about 4 carbon atoms.

2. A fuel as defined by claim 1 wherein said salt is an alizylene polyarnine salt of a petroleum sulfonate.

3. A fuel as defined by claim 1 wherein said salt is an aiirylene polyarnine salt of a polypropyl benzene sulfonate containing from about 9 to about 15 carbon atoms in the polypropyl group thereof.

4. A petroleum distillate fuel boiling in the range between about 300 F. and about 900 F. having incorporated therein as a stabilizing agent from about 0.05% toabout 0.1% by weight of an allrylene polyamine dinonyl naphthalene sulfonate wherein the alkylene polyamino group contains from 2 to about 4 carbon atoms.

5. A fuel as defined by claim 4 wherein said sulfonate is ethylene diamine dinonyl naphthalene sulfonate.

6. A petroleum distillate jet engine fuel boiling between about 300 F. and about 600 F. to which has been added from about 0.05% to about 0.1% by weight of an ethylene diamine salt of a sulfonic acid selected from the group consisting of petroleum sulfonic acid and synthetic sulfonic acid prepared by the sulfonation of an alkylated aromatic hydrocarbon as a stabilizing agent.

7. A petroleum distillate jet engine fuel boiling between about 300 F. and about 600 F. to which has been added from about 0.05% to about 0.1% by weight of ethylene diamine dinonyl naphthalene sulfonate as a stabilizing agent.

References Cited in the file of this patent UNITED STATES PATENTS 2,533,303 Watkins Dec. 12, 1950 2,582,733 Zimrner et al. Jan. 15, 1952 2,684,292 Caron et al July 20, 1954 

6. A PETROLEUM DISTILLATE JET ENGINE FUEL BOILING BETWEEN ABOUT 300*F. AND ABOUT 600*F. TO WHICH HAS BEEN ADDED FROM ABOUT 0.05% TO ABOUT 0.1% BY WEIGHT OF AN ETHYLENE DIAMINE SALT OF A SULFONIC ACID SELECTED FROM THE GROUP CONSISTING OF PETROLEUM SULFONIC ACID AND SYNTHETIC SULFONIC ACID PREPARED BY THE SULFONATION OF AN ALKYLATED AROMATIC HYDROCARBON AS A STABILIZING AGENT. 